changed()

Wait until the value changes from its initial value.

Signature

changed(options?: UntilToMatchOptions): Promise<T>

Parameters

options

• Type: UntilToMatchOptions
• Required: No

Options for timeout behavior.

Returns

A Promise that resolves to the new value when it changes.

Examples

Basic Usage

import until from 'untiljs'

let value = 'initial'
setTimeout(() => { value = 'changed' }, 1000)

const result = await until(() => value).changed()
console.log(result) // 'changed'

With Timeout

import until from 'untiljs'

let value = 'initial'

const result = await until(() => value).changed({ timeout: 5000 })

if (result !== 'initial') {
  console.log('Value changed to:', result)
}

Waiting for State Change

import until from 'untiljs'

let status = 'pending'

async function process() {
  // Some async operation
  setTimeout(() => { status = 'complete' }, 1000)
}

process()

await until(() => status).changed()
console.log('Status changed from pending')

With Vue

import { ref } from 'vue'
import until from 'untiljs'

const loading = ref(false)

async function fetchData() {
  loading.value = false

  setTimeout(() => {
    loading.value = true
  }, 500)

  // Wait for loading to become true
  await until(loading).changed()

  console.log('Loading state changed')
}

With React (createStore)

import until, { createStore } from 'untiljs'

const store = createStore('initial')

async function updateValue() {
  setTimeout(() => {
    store.value = 'updated'
  }, 1000)

  await until(store).changed()
  console.log('Value changed to:', store.value)
}

Object Changes

For objects, use deep option to detect deep changes:

import until from 'untiljs'

let obj = { count: 0 }
setTimeout(() => {
  obj = { count: 1 }
}, 500)

// Detect reference change
await until(() => obj).changed()

// Or with deep comparison for same reference mutations
let obj2 = { count: 0 }
setTimeout(() => {
  obj2.count = 1 // Same reference, different content
}, 500)

// This won't detect the change (reference is same)
// Use toMatch instead
await until(() => obj2.count).toMatch(v => v === 1)

See Also

• changedTimes()
• toMatch()